The Beijing Research Institute of Chemical Industry and Shanxi Research Institute of Chemical Industry, etc., engaged in the research of PVC processing aids earlier in China. The Shanghai Coral Chemical Plant first realized industrial production in the early 1980s, and the brands it launched were collectively referred to as ACR201 and ACR401 in China. PVC is one of the world's five major general-purpose plastics. In recent years, with the rapid development of my country's national economy, PVC products have grown at an annual rate of more than 20%. In the late 1990s, with the development of my country’s PVC industry, especially the rapid development of plastic profile and plastic pipe industry, the demand for processing aids also increased rapidly. Shandong’s output is currently the first, followed by Jiangsu and Zhejiang. Afterwards.

As processing aid manufacturers deepen their understanding of PVC plasticization mechanism, PVC processing technology and PVC equipment, processing aid manufacturers have developed a series of processing aids for the defects of processing equipment and performance defects of PVC products. These processing aids are fundamentally different from traditional processing aids, breaking through the limitations of traditional processing aids, and solving a series of practical problems that traditional processing aids cannot solve. Specifically, PVC processing aids are making major breakthroughs in the following directions.

Super plasticizing processing aid

It is suitable for large amount of filler, large amount of external slip, and weak equipment shearing force. It is necessary to greatly increase the shear force, strengthen plasticization, and increase the strength of the melt. The viscosity is very large, which can compensate for the weak shear force of the equipment and the filling in the formula. The decrease in melt viscosity caused by the large amount of material breaks through the defects of low melt viscosity when the plasticization speed of the traditional processing aid is fast and the slow plasticization speed when the melt viscosity is high.

Super melt strength type processing aid

It is suitable for use when the amount of filler is large, the shearing force of the equipment is strong, and the melt strength needs to be greatly improved. The characteristic of this type of processing aid is that its plasticization speed is average, but the melt viscosity is large, which is more than 3 times that of the traditional processing aid AcR-401.

Lubricating processing aid

Lubricants, especially external lubricants, can reduce the external friction between the melt and the metal surface, prevent the melt surface from cracking, and improve the surface finish of the product. However, if the shear force of the equipment is weak and the plasticizing ability is not strong enough, add an external slip agent It will cause poor plasticization of the product and decrease the mechanical properties. At the same time, the addition of low-molecular-weight lubricants will cause precipitation and shorten the driving time. In order to avoid precipitation and poor plasticization caused by excessive use of external slip agents, lubricating processing aids can be used.

Processing aids to increase the hardness of PVC products

There are many factors that affect the hardness of PVC products. Under the premise of the same formula, greatly increasing the shear and increasing the melt pressure can minimize the residual amount of various low-melting external slip agents inside the product, thereby greatly increasing Increase the Vicat softening point and hardness of the product. This type of processing aid is characterized by a higher glass transition temperature and a lower melting point. The lower melting point is to ensure a fast plasticization speed, to extend the plasticization experience of PVC, to fully plasticize the PVc, and to increase the average glass transition temperature of the low melting point to increase the Vicat softening point and hardness of PVc products.

ACR for pipe fittings

The processing of PVC pipe fittings requires that the PVC melt must have the characteristics of sufficient plasticization, high melt strength and good fluidity, but good fluidity and high melt strength are a contradiction. Generally, the fluidity is poor when the melt strength is high. Traditional processing aids overemphasize melt strength and ignore fluidity, which makes the surface gloss of PVC pipe fittings poor, and butterfly spots appear in severe cases. In order to solve the above problems, the pipe fitting manufacturer added a plasticizer. Although the gloss of the pipe fitting was obviously improved, the mechanical properties were greatly affected. The new AcR for pipe fittings adopts a special formula, which greatly improves the fluidity of the melt while ensuring the strength of the PVC melt, and ensures that the surface gloss of the pipe fittings is greatly improved on the premise of good internal quality.

In addition to the several types of processing aids introduced above, there are also processing aids that can improve the surface gloss of products and increase the fillet strength of profiles. PVC processing aids have evolved from the traditional ACR-201 and ACR-401 to multi-functionality, and there are more and more types of products. Certain defects of PVC products are matched with corresponding processing aids. Tailoring and tailoring have become a major trend in the PVc processing aid industry, and new processing aids will emerge in endlessly.

PVC is easy to decompose when its pure resin is processed, has poor fluidity, low impact strength, and poor weather resistance. Therefore, various auxiliary materials need to be added during the processing to improve its performance. Such as: lubricants, heat stabilizers, impact modifiers, processing aids, etc. In the process of development and application of processing aids, product components are roughly divided into the following categories: methyl methacrylate (MMA)/acrylate copolymer, MMA/styrene copolymer, acrylonitrile/styrene, etc. The most used and effective is MMA/acrylate copolymer.

PVC processing aids were first developed abroad by Rohm & Hass in 1958, and the first brand K-120 was launched in the same year. Since then, many foreign companies have stepped into this field and developed similar products. After the 1970s, with the rapid growth of PVC products, processing aids have been widely used. At present, the major foreign manufacturers and related products include the P series of MITSUBSHIROYAL, the PA series of KANEKA, the K series of Rohm & Hass, the K series of German bear brand (BEAR) F series, Tofina (ATOFINA) P series, as well as South Korea's LG Chem's PA series, etc.